Sunday, August 23, 2009

Wire transmission

Scottish inventor Alexander Bain worked on chemical mechanical facsimile type devices and in 1846 was able to reproduce graphic signs in lab experiments. Frederick Bakewell made several improvements on Bain's design and demonstrated his device at the 1851 Great Exhibition in London. Bain and Bakewell's systems were inferior and could reproduce only poor quality images. They lacked synchronization between the transmitting mechanism and the receiving mechanism. In 1861, the first practical operational electro-mechanical commercially exploited telefax machine, the Pantelegraph, was invented by the Italian physicist Giovanni Caselli. He introduced the first commercial telefax service between Paris and Lyon some 11 years before the invention of workable telephones.[1][2]In 1881, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, not requiring manual plotting or drawing anymore. Around 1900, German physicist Arthur Korn invented the Bildtelegraph, widespread in continental Europe especially since a widely noticed transmission of a wanted-person photograph from Paris to London in 1908, used until the wider distribution of the radiofax. Its main competitors were the Bélinograf by Édouard Belin first, then since the 1930s the Hellschreiber, invented in 1929 by Rudolf Hell, a pioneer in mechanical image scanning and transmission